1. Field of the Invention
The present field relates to navigating in a geographic information system.
2. Related Art
A geographic information system (GIS) is a system for archiving, retrieving, displaying or manipulating data indexed according to the data elements' geographic coordinates. The data element may be a variety of data types such as, for example, imagery, maps, models of buildings and terrain and other geographic features.
A geographic information system may display a three-dimensional environment to a user from a perspective of a virtual camera. The perspective of a virtual camera may be defined by a position and orientation. By changing the position and orientation of the virtual camera, the user can sightsee within the three-dimensional environment. For example, the user may “visit” the Eiffel Tower in the GIS by directing a perspective of a virtual camera toward a representation of the Eiffel Tower.
A perspective of a virtual camera may be stored in a language such as Keyhole Markup Language (KML). Interpreting the KML, a GIS may move the virtual camera to a stored perspective to display a sight. Using the stored perspective, a user can return to the sight. Further, KML can store a sequence of perspectives. Interpreting the KML, the GIS may move the virtual camera iteratively from one perspective to the next. This enables the user to tour a series of sights, e.g., the Eiffel Tower, Big Ben, etc. However, editing the KML defining a tour can be cumbersome for the user.